Perforator



Sept. 29, .1970 H. u. GARRETT 3,530,948

I PERFORATOR Filed June 20, 1968 5 Sheets-Sheet 1 HENRY U. GARRETT IN ENTOR.

Sept. 29, 1970 H, GARETT 3,530,94

PERFORATOR Filed June 20, 1968 United States Patent 01 ifice' 3,530,948 Patented Sept. 29, 1970 US. Cl. 175-4.51 Claims ABSTRACT OF THE DISCLOSURE This patent discloses a perforating apparatus which is preferably pumped into and out of a well. The apparatus is laudable in a tubing and the gun is fired by hydraulic pressure. This abstract of disclosure does not limit the invention or interpret the claims.

This invention relates to a perforating apparatus, and more particularly to a perforating apparatus which is fired hydraulically.

It has been customary to perforate tubing by running a perforating gun on a wireline. The gun is usually discharged electrically.

There are instances, particularly in offshore operations, where it is difficult to utilize a wireline because the tool must turn a sharp radius bend at the surface before proceeding down into the hole.

Recently there has been devised a method of hydraulically running and retrieving gas-lift valves. See Pat. No. 3,334,690. This invention is an improvement and may be utilized with the system shown in said patent.

It is an object of this invention to provide a perforating apparatus for wells which can be fired hydraulically.

Another object is to provide a perforating apparatus for wells which can be pumped into and out of a well and fired by hydraulic pressure.

Another object is to provide a perforating apparatus which is hydraulically fired but will not fire prematurely as when being pumped through tight places in the tubing string.

Another object is to provide a perforating apparatus which cannot fire until it is landed in the proper mandrel.

Another object is to provide a perforating gun which will not accidentally fire at the surface when loading.

Other'objects, features and advantages of the invention will be apparent from the drawings, the specification and the claims.

In the drawings, therein like reference numerals indicate like parts;

FIG. 1 is a view partially in cross section with some of the equipment shown in quarter section and some in elevation, illustrating an apparatus in accordance with this invention being pumped to its location;

FIGS. 2A and 2B are similar to FIG. 1 and show the apparatus in landed position in the mandrel and the gun to have been fired. FIG. 2B is a continuation of FIG. 2A with a slight duplication of structure to show the entire latch mechanism in FIG. 2B;

FIG.'3 is a view partially in cross-section and partially in quarter-section illustrating the details of the perforating gun;

FIG. 4 is a view partly in elevation, partly in cross section and partly in quarter section illustrating a modified gun; and

FIG. 5 is a view partly in cross section and partly in elevation illustrating the gun of FIG. 4 run on a wire line.

When a flowing well is first completed there is no need for gas-lift operations. However, in anticipation of the future need to gas-lift the well, it is preferred to provide for gas-lift without the necessity of pulling the string to make equipment changes.

In accordance with this invention, a number of mandrels are made up in the tub-ing string when it is first run. Each of these mandrels 9 will have landing grooves, such as indicated generally at 10, with which landing dogs, which are indicated generally at 11, cooperate to land a tool in a mandrel. The profile of the grooves difiers in each of the mandrels. The profile of the dogs also differs and is designed to mate with a particular mandrel, and no other mandrel on the string. Thus, a tool may be run with latching dogs with the assurance that the tool will land in a particular position in the string. Alternatively, plugs may be set in the tubing, but this is not preferred. The plug technique will permit the use of the perforating gun illustrated in this application in the event mandrels have not been provided. When it is desiredto "place the well on gas-lift, the mandrels are perforated and gas-lift valves are landed in the mandrels either by wireline or hydraulically as disclosed in Pat. No. 3,334,690.

In accordance with this invention, a perforating gun which is indicated generally at 12 is run into the hole hydraulically. The gun is illustrated in FIGS. 1 and 2A in elevation to emphasize that the particular construction of the gun is unimportant to this invention. A projectile may be used or shaped charges maybe used. The manner of handling and firing the projectile or shaped charge, or the like, may take any desired design.

The assembly is pumped into and out of the well utilizing a motor indicated generally at 13. This motor includes a packer body 14 which is closed at its lower end except for a bleed passage 15. The packer body is secured to the equipment above and below by swivel joints indicated generally at 16 and 17 to permit the apparatus to turn about a short radius bend. A packer which seals against pressure in both directions is provided on body 14 and may take any desired form. For instance, the lip-type packers 18 may be utilized. These packers have a series of lips 18a looking upwardly and a series of lips 18b looking downwardly to seal against fluid bypass in either direction up to their design capacity. If a differential across the packer body exceeds this differential, the lips will permit flow thereby.

A metal labyrinth-type seal is provided by the member 19 secured to the upper end of the packer body 14. This seal member has a smaller diameter than the tubing, but in the event of failure of the packer will function as a leaky packer to permit movement of the assembly through the tubing 20.

The perforating gun 12 is fired by the firing mechanism indicated generally at 21 in response to hydraulic pressure. The firing mechanism includes a body 22 having a chamber 23 therein. One wall of this chamber is provided by a pressure-responsive member which may be piston 24. In the illustrated embodiment the body 22 includes the male portion 25 of a swivel joint which secures the firing mechanism to the gun 12. A rod 26 is carried by the piston 24 and may be an integral part thereof. Suitable seals, such as O-rings 27, 28 and 29, are provided between the body, piston and rod so that the chamber 23 is a sealed chamber. Preferably, this chamber is at atmospheric pressure.

The piston 24 is exposed to pressure outside the chamber through a plurality of ports 31 which extend through the body 22 to the pressure-responsive member. The port 31 communicates with a chamber 32 below the piston 24. A suitable seal provided by O-ring 33 seals between the piston and body below the chamber 32, and thus the pressure reaching this chamber must pass through the ports 31. It will be appreciated that when a pressure is exerted on the piston 24 which is greater than atmos- 3 pheric, it will tend to move the piston upwardly. This upward movement of the piston fires the perforating gun. In order to control the firing of the perforating gun, means are provided for holding the piston 24 in a retracted position until the pressure exterior of the chamber is greater than the atmospheric pressure within the chamber by a selected amount. A shear pin 34 preferably holds the piston in retracted position in the body and releases the piston by shearing when the selected differential across the piston is present. Thus, when the pressure exerted on the piston 24 reaches the desired level, the pin 34 shears and the piston moves upwardly to fire gun 12. This pressure is exerted by pressuring up the tubing, and to confine this pressure the packing assembly 35 on body 22 is preferably provided. This prevents loss of fluid into the annulus between the tubing 20 and the casing 36 when perforations exist below the gun when it is fired.

The gun is selectively landed in a mandrel indicated generally at 10 by the landing dogs indicated generally at 11. As noted above, the groove configuration 36 in the mandrels differs in each case and may take any selected configuration. The landing dogs are contoured by providing lands and grooves 37, 38 and 39 to conform to the profile of the grooves 36. The profile of the grooves and dogs selects the mandrel in which the assembly will land. To prevent further downward movement, confronting shoulders normal to the central axis of the tubing are provided as at 41 on the dogs and at 42 in the tubing. One or more of the downwardly facing shoulders on the dogs and cooperating shoulders in the mandrel may have this normal configuration. All of the shoulders facing upwardly, such as 43 and 44 on the dogs, and 45 and 46 on the mandrel, are upwardly and inwardly inclined so that pressure below the packer 13 will be effective to disengage the dogs and permit the assembly to be pumped out of the well.

While any landing device may be utilized, the device illustrated is preferred. A plurality of dogs such as indicated generally at 11, are hinged about the pins 45a. A spring 46a associated with each dog urges it to swing outwardly in a radial direction about its pivot point and set in the mandrels.

Means are provided to prevent firing of the gun until the apparatus is landed in a tubing mandrel. Preferably this means is associated with the dogs and the gun is prevented from firing until the dogs have swung to their landed position. For this purpose a restraining connection is provided by the piston 24 and a flange 47 on one or more of the dogs 11. This flange is effective while the dogs are in retracted position and is ineffective when they move to expanded position. In the illustrated structure, the piston 24 is provided with a guide 48. The guide has a cap 49 thereon with an exterior ball-like surface which cooperates with the sleeve 50. The sleeve 50 has an upper section which is inturned and provides a socket to engage the ball 49. The sleeve 50 is reciprocally mounted within the swivel joint indicated generally at 51.The sleeve 50 has a nut 52 on its lower end which engages an out-turned flange on the upper latch member 53. The lower latch member 54 is threaded to the member 53 and carries an annular out-turned flange 55 which engages the flange 47 on the dog 11 when the dogs are retracted. Thus, a firm mechanical connection exists from the landing dogs to the piston 24 which prevents upward movement of the piston 24 until the dogs are extended. This prevents premature firing of the gun. A spring 56 urges the member 54 upwardly so that after the gun is seated and fired, the annular flange 55 will be above the retaining member 47 to permit the dogs to readily retract. This relationship is illustrated in FIG. 2.

Reference is now made to FIG. 3 in which a form of gun is illustrated which may be used with this invention. The firing rod 26, when driven upwardly by hydraulic pressure, strikes the firing pin 57. In order to prevent a hydraulic block, a plurality of ports 58 and 58a are provided to permit fluid to be driven out of this portion of the gun by upward movement of the piston 24. The firing pin, upon being struck, activates the cartridge 59 which fires the charge 60. Upon firing of the charge 60, the wedge member 61 is driven upwardly. The wedge surface 62 on member 61 cooperates with a mating surface 63 on projectile 64. This projectile was initially held in position by a wire retainer 65 which extends through the large projectile and the body 66 of the gun. A shock-absorbing member 67, preferably of nylon, is struck by the wedge member 61 at the end of its travel.

As the projectile 64 is driven outwardly, it drives the shear member 68 through the wall of the tubing. The large projectile strikes the tubing and stops and the shear member continues on through the tubing and drops into the space in the tubing-casing annulus.

In operation, the tubing string 20 is run with a plurality of mandrels 69 thereon. It will be noted that the inner diameter 69a of the mandrels is slightly less than the inner diameter of the tubing. When it is desired to gas-lift the well, the performing apparatus is run into the tubing as illustrated in FIG. 1. Preferably in making the lowermost perforation, the packing 35 is omitted. A set of landing dogs 11 is selected to conform with the lowermost mandrel to be perforated.

The tool is introduced through the customary lubricator and pumped down the well against formation pressure until the tool is landed. As the formation pressure will not be substantial when a well is placed on gas lift, no problem will be encountered in pumping against formation pressure. An increase in pressure at the well head will indicate landing of the tool. Up to this time the gun could not fire as the piston 24 is held in retracted position by the retracted dogs 11. Even if it is necessary to exceed the pressure necessary to shear pin 34 to drive the assembly through a tight place in the casing, the gun will not fire until it lands in the proper mandrel. Normally, however, the pin will not be sheared until the assembly lands.

After the operator receives his indication of landing by a sudden rise in pressure, he increases pressure to the extent needed to supplement the hydrostatic head of pressure on the tool and shear pin 34. At this time the piston 24 moves upwardly rapidly due to the differential thereacross and fires gun 12.

After the gun has been fired, the port 70 establishes communication between the tubing and the tubing-casing annulus. The pressure is removed from the tubing and applied to the tubing-casing annulus to pump the tool out of the well. It should be noted that the packing 35 could be run on the tool in making the first perforation, and the differential in area between the tubing and mandrel relied upon for pumping the tool upwardly to clear the perforations.

The tool is withdrawn from the well, the gun reloaded, and the tool run again. In reloading, a thin tool is inserted between the dogs and their carrier to pull the lower latch member 54 downwardly. The appropriate dog is then swung to retracted position to hold latch member 54 in retracted position. The latching dog profile will be selected to mate with the grooves in the No. 2 mandrel to be perforated reading from the bottom. In this perforation and in all perforations thereabove, the packing 35 is preferably included so that it will not be necessary to pump against the formation and through the ports 70 previously perforated.

After making the second perforation, the fluid in the casing is effective on the difference in area between the two packings through the second perforation on the whole tool through the lower perforation previously made, and therefore ample area is present against which reverse fluid pressure may be exerted to lift the tool from the hole.

After all of the mandrels to be perforated have been perforated, gas-lift valves may be seated in the mandrel in the manner taught in Pat. No. 3,334,690; that is, by making up a series of mandrels which land in the tubing mandrels on a motor. Each of the mandrels carries a gas-lift valve. As the train moves down the hole, the mandrels are dropped off from the rear, one by one, until the motor lands in the lowermost mandrel and is locked in place. When the valves are to be retrieved, pressure is manipulated to release the motor and the train is pumped out of the hole. Of course, the several valves could be run in the hole by wireline, as could the perforating apparatus disclosed herein, but it is preferred that all of the apparatus be run hydraulically.

While the chamber 23 is preferably at atmospheric pressure, it is apparent that pressure in the tubing below the packing 35 could be present in this chamber by a suitable connecting passageway, as it is only necessary that a desired dilferential across the piston be exerted to fire the piston.

A modified form of apparatus is shown in FIG. 4. The perforating gun 71 is preferably run iby a packing such as shown at 13 in FIG. 1 carried on the mandrel 72.

The perforating gun includes a housing 73 which is secured to the mandrel 72 by a solid sub 74. A nipple 75 is secured to the lower end of the housing.

A perforating means, such as the projectile indicated generally at 76, is carried in the housing 73. There may be one or more of the perforating means and any form of perforator may be utilized. A primer cord 77 extends from the perforating means 76 to a cartridge 78 which is fired by a firing pin 79 reciprocal in a suitable support 81. The support 81 is fastened to the lower end of the nipple 75 by nut 82.

The apparatus for firing the perforating gun includes a tubular body 83. An external seal indicated generally at 84 is carried on the body between the sleeve 85 and the nut 86. The sleeve 85 and nut 86 straddle flange 87 to hold the packing in the desired position on the body.

A pressure-responsive member provided by piston 88 is reciprocally mounted in bore 89 on body 83. The piston 38 is provided with a sliding seal with the bore 89 by the O-ring 91. The piston 88 is solid in the area of the O-ring. Extending upwardly from the solid portion of the piston is a tubular section 92 which is connected by threads to the nut 81 to thus secure the piston to the perforating gun.

Means are provided which are responsive to movement of the pressure-responsive member 88 relative to body 83 to strike firing pin 79 and fire the perforating gun. In this embodiment the means for firing the gun includes a striking member 93 which is reciprocally positioned in the bore 94 provided in the upper tubular section 92 of piston 88. A suitable pin 95 pins the striking member 93 to the body 83. The upper tubular portion 92 of the piston 88 is provided with vertical slots 96 to permit relative movement of the body and piston 88.

Means are provided for preventing firing of the gun until the tool is landed in the well by providing a nut 97 on the lower end of piston 88. The nut has a radially extending surface 98 which engages a complementary surface 99 on the latching mechanism indicated generally at 101 to prevent downward movement of the nut and piston 88 when the latching dogs are retracted.

The latching assembly 101 is the same as that shown in FIGS. 1, 2A and 2B.

Means are provided for holding the piston 88 in a first position and releasing the piston for movement in response .to a selected pressure differential thereacross to another position in which the firing pin 79 is struck by striking member 93 to fire the gun. In the illustrative embodiment, this means is provided by shear pin 102.

In the event the lower section of the apparatus sticks or has trouble passing through a tight spot in the tubing, the upper end of housing 83 has a nut 103 thereon 'which engages the out-turned flange 104 immediately therebelow to transmit pulling force between the perforating gun and the housing 83.

In operation, the assembly shown in FIG. 4 is pumped into the well by a suitable motor such as packing 13 (FIG. 1) until the dogs of the latching assembly 101 mate with suitable landing grooves 105 in mandrel 106. Previous to this time the gun could not fire due to cooperation of surfaces 98 and 99. After the tool is landed, tubing pressure above the tool is increased to exert a downward force on the upper face of the pressure-responsive member provided by piston 88. As this pressure is increased to a selected value above the pressure acting upwardly on the other face of the pressureresponsive member, the pin 102 is sheared. Upon shearing of pin 102, the piston 88 moves downwardly and pulls the firing pin 79 into engagement with the striking member 93 to fire the cartridge 78 and thus fire the perforating gun.

In FIG. 5 the tool is shown run on wireline 107. After the tool is landed the wireline is lowered to provide adequate slack and the tubing pressured up to shift the piston 88.

While the tool has been shown in conjunction with mandrels having landing grooves therein, it is obvious that a plug could be set in the well at a desired depth and the tool supported on the plug in lieu of the latching assembly 101. After firing, the tool and plug would be removed and a gas-lift valve positioned in the tubing by straddle packers above and below the perforation.

It is obvious that while concentric tubing-casing type of completion has been illustrated, the perforating device will work equally well in a situation where two tubings are present inside of a casing. If the two tubings are joined at the bottom, an additional passageway is provided for U-tubing the apparatus out of the well. Additionally, it is contemplated that parallel tubing may be run with mandrels which are secured to each of the tubings and are connected by firing a projectile or charge through a suitable wall in the mandrel.

If it is desired to shoot successive holes commencing at the top of the tubing, dummies can be carried on a train and landed in mandrels as the train moves down the tubing to block the previosuly perforated port.

I claim:

1. A perforating apparatus comprising,

a perforating gun,

a body having a chamber therein,

a pressure-responsive member providing a wall of the chamber and exposed to pressure exterior of the chamber,

means holding the pressure-responsive member in a retracted position and releasing the pressure-responsive member in response to a selected pressure exterior of the chamber which pressure is greater than the pressure within the chamber,

means responsive to movement of said pressure-responsive member for firing said gun, and means for landing the apparatus in a tubing including landing dogs for preventing movement of the pressure-responsive member until the dogs move into landing position.

2. A perforating apparatus comprising,

a perforating gun,

a body having a chamber therein,

a pressure-responsive member providing a wall of the chamber and exposed to pressure exterior of the chamber,

means holding the pressure-responsive member in a retracted position and releasing the pressure-respon sive member in response to a selected pressure exterior of the chamber which pressure is greater than the pressure within the chamber,

means responsive to movement of said pressure-responsive member for firing said gun,

means for landing the apparatus in a tubing, and safety 3. A perforating apparatus comprising,

a perforating gun,

a body,

a pressure-responsive member in the body having at least one pressure-responsive face exposed to pressure exterior of the body,

means holding the pressure-responsive member in one position and releasing the pressure-responsive member for movement in response to a selected pressure differential across the pressure-responsive member to another position,

means responsive to movement of said pressure-responsive member for firing said gun,

means for landing the apparatus in a tubing, and

safety means preventing movement of the pressureresponsive member until the apparatus is landed.

4. A perforating apparatus comprising,

a perforating gun,

a body having an external packing thereon adapted to engage the wall of a tubing and prevent flow of fluid past the body,

a pressure-responsive member in the body having one pressure-responsive face exposed to exterior pressure on one side of the packing and the other pressure-responsive face exposed to external pressure on the other side of the packing,

r 8 a means holding the pressure-responsive member in one position and releasing the pressure-responsive member for movement in response to a selected pressure differential across the pressure-responsive member to another position, and means responsive to movement of said pressureresponsive member for firing said gun. 5. The apparatus of claim 4 wherein means are provided for landing the apparatus in a tubing, and safety means are provided preventing movement of the pressureresponsive member until the apparatus is landed.

References Cited UNITED STATES PATENTS 2,749,840 6/1956 Babcock 175-4.56X 3,032,109 5/1962 Corley et al 1754.56 3,040,808 6/1962 Schramm et al. 175--4.54X 3,058,522 10/ 1962 McElheny 1754.5-4 3,150,717 9/1964 Otteman et a1 166-155 X 3,391,263 7/1968 Young 175-454 X DAVID H. BROWN, Primary Examiner US. Cl. X.R. 

